NUSC 1165 Lecture Notes - Lecture 11: Chyme, Pepsin, Gastrin
Document Summary
Bolus of food enters stomach through the lower esophageal sphincter. Messages (from hormones) are sent from the stomach. When bolus mixes with stomach juices, it becomes chyme. That chyme is squirted out of stomach. Binds to a receptor on the stomach (h2 receptors) Tells the stomach to do something about the food. The stomach receives the message and releases acid. Pepsinogen is an inactive enzyme that is activated by acid. Pepsin starts to break down protein chains called polypeptides. Allows protein to be absorbed into blood. Released when the stomach expands or high fat. Travels to the brain to increase appetite. Gastrine travels in blood, back to stomach. Acid activates pepsin to break down protein. Stomach also releases cck to say its full. If you do not eat: ghrelin is released. All of these gastric juices need to get to the small intestines. Nerves fire to squeeze and relax stomach muscles. Peristalsis: wave-like muscular movement of stomach to move food.